fix(formula): hydrate string-serialized numeric fields in CEL comparisons (#1534)

[os-zhuang]

Summary

Fixes #1534. Record-change flow decision / edge conditions that compare a numeric field against a literal (record.rating >= 4, record.amount > 100000) faulted at runtime whenever the field's value serialized as a string — Field.rating(allowHalf) → "5.0", Field.currency(scale) → "250000.00", Field.percent likewise. Strict CEL raised no such overload: dyn >= int, so the comparison could never be satisfied and the flow silently dead-ended at the decision node (no edge matched, success: true, nothing downstream ran).

Root cause

The bound field value is the raw, string-serialized row value, while the build-time validator (ADR-0032 §1a) and schema treat the field as numeric — a build-vs-runtime mismatch. cel-js is strict: string <op> number has no overload.

Fix

The shared @objectstack/formula CEL engine (cel-engine.ts) now retries an evaluation once with purely-numeric strings hydrated to numbers — but only after a no such overload fault. Key safety property:

• A comparison that already type-checks (e.g. record.zip == "02134", string == string) never enters the retry path, so it is never re-interpreted.
• The retry only ever rescues an evaluation that already faulted — it can never change a currently-passing result.
• A genuinely non-numeric operand (e.g. record.rating >= 4 where rating is "high") still faults loudly; if the retry can't type-check, the original error is surfaced (ADR-0032 §1c/§1d — fail loudly, never swallow).

Because both projection paths the issue calls out route through ExpressionEngine.evaluate — service-automation's evaluateCondition and objectql's applyFormulaPlan — fixing the shared engine resolves them consistently, as requested in the issue's relationship to #1530.

The "silent dead-end" half is already covered on main: evaluateCondition throws an attributed error on a non-ok CEL result (the #1491 fix), which execute() records as a loud failed run. With this change the common numeric-string case no longer faults at all.

Tests

• packages/formula/src/cel-engine.test.ts — new numeric-string field hydration suite: rating "5.0" >= 4, currency "250000.00" > 100000, percent, previous.* transition gates, compound predicates, unmet compares returning false (not a fault), genuine string equality left untouched, and non-numeric strings still faulting.
• packages/services/service-automation/src/engine.test.ts — end-to-end: a record-change flow routes through a decision node's record.rating >= 4 edge (rating "5.0") to the hot-lead branch instead of dead-ending.

All formula (82) and automation (98) tests pass.

Scope note

The arithmetic case (record.amount + 100 on a hydrated number) hits a separate cel-js limitation — double + int literal has no overload even for genuine numbers — and is out of scope for this comparison-focused issue.

https://claude.ai/code/session_01FjtHqsTWWPThCP6jsVdvPa

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